The present invention relates to a control and supervisory system for power distribution equipment, and more particularly, it relates to a control and supervisory system which is able to make up a network from respective pieces of supervisory and control information about various kinds of power distribution devices including protective equipment such as non-fusible circuit breakers, earth-leakage breakers, etc., electromagnetic switches for on-off control, remote-controlled equipment, and metering equipment such as transducers, watt-hour meters, etc.
Among these types of conventional control systems, a typical power distribution equipment control and supervisory system is diagrammatically shown in FIG. 1. The system illustrated generally includes a central control and supervisory unit (hereinafter referred to as a main device) 1 having a built-in microcomputer, and a plurality of terminal control and supervisory units (hereinafter referred to as terminal devices) 3 connected to the main device 1 through a signal transmission line 2 for controlling and supervising a plurality of power distribution devices 7 each of which controls, protects and supervises a corresponding electric load. Each of the terminal devices 3 receives a control signal transmitted from the main device 1 via the signal transmission line 2 and sends it out to the corresponding power distribution device 7, whereas a signal inputted from a power distribution device 7 to the corresponding terminal device 3 is returned to the main device 1 via the signal transmission line 2.
A more concrete example of the above mentioned control and supervisory system is illustrated in FIG. 2. The system illustrated is a load control apparatus for a power distribution system utilizing a private multiplex transmission as described in Japanese Patent Publication No. 59-29998. In FIG. 2, the load control apparatus includes a central control and supervisory device (i.e., a main device) 1, a plurality of terminal devices 3 each adapted to receive a control signal from the main device 1 through a signal transmission line 2, a multitude of electric loads 4, a commercial power source 5 for supplying power to the respective loads 4 through power lines 6, and a plurality of power distribution devices 7 in the form of on-off control switches provided one for each load 4 and adapted to be each operated by the control output of a corresponding terminal device 3 for controlling the power supply from the power source 5 to a corresponding electric load 4.
In this type of load control apparatus, a signal, which is shown in FIG. 3(a), is transmitted from the main device 1 to the terminal devices 4 through the signal transmission line 2. This type of control in the above load control apparatus is commonly performed in many other similar apparatuses which utilize private multiplex transmission. In FIG. 3(a), P.sub.1 designates a start pulse indicative of the starting of a signal transmission; P.sub.2 a terminal address pulse indicative of the addresses of the terminal devices 3; and P.sub.3 a control pulse indicative of control signals inputted from the main device 1 to the terminal devices 3.
Each of the terminal devices 3 makes a comparison between its self terminal address stored therein and the terminal address pulse P.sub.2 inputted thereto from the main device 1. If a particular terminal device 3 determines that they coincide with each other, then it generates an address-coincidence signal, as illustrated in FIG. 3(b), and a latch output, as illustrated in FIG. 3(c), whereby the corresponding control switch 7 is closed so as to supply power from the power source 5 to the corresponding electric load 4.
In this connection, it will be readily understood that in the case where the main device 1 is intended to perform supervisory operation, the above control procedure can also be utilized to realize the function of collecting information about the on/off conditions of switch signals which are inputted from the control switches 7 to the respective terminal devices 3.
A more concrete description will now be made of the case in which this type of control and supervisory system is applied to controlling and supervising an earth-leakage breaker equipped with an electrically operated device. FIG. 4 shows one example of such a system. In this figure, the system illustrated includes a main device 1 in the form of a central control and supervisory unit, a terminal device 3 adapted to be operated by a control and supervisory signal which is inputted thereto from the main device 1 through a signal transmission line 2, an electric load 4 in the form of an electric motor, a main circuit power source 5, a power line 6 for supplying power from the main power source 5 to the load 4, and a power distribution device 7 in the form of an earth-leakage breaker 7 connected between the main circuit power source 5 and the load 4. The earth-leakage breaker 7 includes a power terminal 7a, a switch 7b, a load terminal 7c, an overcurrent trip 7d, a ZCT 7e, and an earth-leakage trip 7f. The system also includes another terminal device 30 which has first through third LEDs 30-1, 30-2 and 30-3 operable in response to a control output of the terminal device 30 to indicate various operating conditions thereof such as, for example, an on-off condition, an overcurrent and shortcircuit trip condition, and an earth-leakage trip condition, a turn-on switch 30-4 in the form of a push button switch for performing a turn-on operation, and a turn-off switch 30-5 in the form of a push button switch for performing a turn-off operation, these switches being operated by an operator for supplying a supervisory input to the terminal device 30.
The system further includes an electrically operated device 8 associated with the earth-leakage breaker 7 in such a manner as to externally operate the switch 7b, an auxiliary contact 9 adapted to be operated to close or open in response to the operation of the switch 7b, an alarm contact 10 operable to generate an output based on the output of the overcurrent trip 7d, and an earth-leakage alarm contact 11 operable to generate an output based on the operation of the earth-leakage trip 7f.
The electrically operated device 8 is operated by an external switch comprising an on-driving control contact 3-1 and an off-driving control contact 3-2 for externally operating the earth-leakage breaker 7 and a circuit breaker. The device 8 is generally constructed such that it can operate a manipulation member in the form of a knob, lever, arm, etc., of the earth-leakage breaker 7 and/or the circuit breaker from the outside. A concrete example of such an electrically operated device 8 is illustrated in FIG. 5. In this figure, the electrically operated device 8 comprises a first and a second diode-bridge circuits 8a and 8c, each including a varistor for absorbing surge; a turn-on coil 8b which is operated by a DC current; a turn-off coil 8d which is operated by a DC current; and a connection terminal 8e having an earth terminal. The device 8 further includes an externally-operated turn-on switch 12, an externally-operated turn-off switch 13, and an auxiliary power source 14 for supplying power to the electrically operated device 8.
The operation of the above mentioned system for controlling and supervising the above earth-leakage breaker 7 by means of the main device 1 in a conventional manner will be described with particular reference to FIG. 4.
First, the main device 1 reads supervisory data from a supervisory input to the terminal device 30 through an appropriate means such as polling, and checks whether the turn-on switch 30-4 is pushed by an operator. If the answer is "NO", the main device 1 does nothing based on the data from the terminal device 30 and goes to another program and executes it. On the other hand, let us consider the case in which the turn-on switch 30-4 is pushed. In this case, if the main device 1 recognizes from the supervisory data response of the terminal device 30 that the turn-on switch 30-4 is pushed, then it starts to execute a program for controlling the earth-leakage breaker 7 in such a manner that the breaker 7 is turned on through the action of the terminal device 3. Here, the case in which the main device 1 operates to turn on the earth-leakage breaker 7 will be described in more detail while referring to FIG. 6 which shows a flow chart of a control procedure therefor.
First, in order to close the on-driving control output contact 3-1 of the terminal device 3 which constitutes the turn-on switch 12 in FIG. 5, the main device 1 outputs a control command in the form of an on-signal output to the terminal device 3 via the signal transmission line 2. Upon receipt of the control command from the main device 1, the terminal device 3 outputs it as an on-driving signal to thereby close the on-driving control contact 3-1. When the contact 3-1 has been fully closed, the terminal device 3 communicates a signal indicative of the closure of the contact 3-1 to the main device 1.
Subsequently, in order to determine whether the earth-leakage breaker 7 is operated in the normal manner by means of the on-driving output of the terminal device 3, the main device 1 sends to the terminal device 3 a supervisory command in the form of a supervisory data read-in command for reading the supervisory data about the earth-leakage breaker 7. Upon receipt of the supervisory command, the terminal device 3 reads, through lines 3-3, 3-4 and 3-5, the contact-input supervisory data (i.e., on/off signals from the AX, AL and EAL contacts 9, 10 and 11), as illustrated in FIG. 4, and sends it to the main device 1 via the signal transmission line 2.
Thereafter, the main device 1 operates to check, based on the supervisory data, whether or not the earth-leakage breaker 7 is performing the turn-on operation in the normal fashion. In other words, the main device 1 checks the contact signal AX which is inputted from the auxiliary contact 9 to the terminal device 3 through the lines 5. If it is determined that the earth-leakage breaker 7 is operating in the normal fashion, the main device 1 sends to the terminal device 3 a turn-on signal release command for terminating the on-driving output of the control output contact 3-1, so that the terminal device 3 is operated to open the turn-on switch 12 of FIG. 5 and terminate the on-driving output. After the termination of the on-driving output, the terminal device 3 communicates the termination to the main device 1 so that the main device 1 finishes the on-driving operation of the earth-leakage breaker 7.
Subsequent to the termination of the turn-on operation, in order to operate the turn-on indicating LED 30-1 of the terminal device 30, the main device 1 operates the terminal device 30 so as to light the LED 30-1 according to the same procedure as described above.
On the other hand, if it is determined that the operation of the earth-leakage breaker 7 is abnormal, an error processing is performed in accordance with a prescribed procedure, and then the main device 1 sends to the terminal device 3 an on-signal release command for terminating the on-signal output, whereby the terminal device 3 is operated to terminate the on-driving output. After the finishing of the on-driving output terminating operation, the terminal device 3 communicates the finishing of the terminating operation to the main device 1.
Thereafter, the main device 1 communicates the abnormal operation of the earth-leakage breaker 7 to the terminal device 30 which then performs its own error processing (e.g., lights an appropriate LED for indicating such an abnormality and inhibits a supervisory input to the terminal device 30) and finishes its operation.
As can be seen from the foregoing description, in the conventional control and supervisory system described above, the main device 1 has to send to the terminal device 3 a predetermined control procedure as required for the above control and supervisory operations so as to directly control the power distribution device 7 such as the earth-leakage breaker through the terminal device 3. Therefore, it is necessary for the main device 1 to prepare and store the required control and supervisory procedures.
With the conventional power distribution device control and supervisory system as described above, varying kinds of groups of power distribution devices are connected to form a kind of network. A minimum unit for controlling and supervising includes, by an output relay contact such as the on-driving or off-driving control output contact 3-1, 3-2 or by a contact input signal from the AX, AL or EAL contact, as shown in FIG. 4. Thus, the main device 1 is necessarily required to output a control or supervisory command in accordance with a predetermined algorithm which is defined by a specific control and supervisory procedure intrinsic to the respective power distribution devices. As a result, the control and supervisory procedures to be stored in the main device 1 become tremendous, increasing the processing time required for executing one control or supervisory command as well as resulting in a very low efficiency in utilization of transmission paths.
Further, in the above-described conventional system, the main device 1 is indispensable for organizing or arranging the entire system in order, and that is true in the even that a small or compact system is constructed. Therefore, in particular, the construction of a relatively small system is costly and requires a relatively large space for installation,
Furthermore, engineers or programmers, who prepare control and supervisory procedures for the main device, have to be familiar with the procedures for permitted and inhibited operations of all the power distribution equipment to be connected with the main device so that algorithms to be prepared are accordingly increased in number and volume, and become much more complicated.